Lens barrel

Abstract

A lens barrel includes an optical system including a short focal length for a wide angle of view; and an ND filter in the shape of a disc which is provided on an optical axis of the optical system. An optical density of the ND filter decreases in a direction radially outwards from a center of the ND filter.

1. A lens barrel, comprising:
 an optical system including a short focal length for a wide angle of view; and 
 an ND filter in the shape of a disc which is provided on an optical axis of said optical system; wherein an optical density of said ND filter decreases in a direction radially outwards from a center of said ND filter, and 
 a shutter unit, wherein said ND filter is fixed to said shutter unit. 
 
   
   
     2. The lens barrel according to  claim 1 , wherein said ND filter comprises:
 a high optical density portion in the shape of a circle which is provided at a center of said ND filter; and 
 a low optical density portion provided around said high optical density portion, 
 wherein a diameter of said high optical density portion is smaller than an effective aperture of said optical system. 
 
   
   
     3. The lens barrel according to  claim 2 , wherein said high optical density portion comprises at least two portions having different optical densities which are arranged concentrically with respect to said center of said ND filter. 
   
   
     4. The lens barrel according to  claim 1 , wherein said optical system comprises a plurality of lens groups which are fixed to a corresponding plurality of lens frames. 
   
   
     5. The lens barrel according to  claim 1 , wherein said ND filter comprises:
 a transparent optical element; and 
 a coating which is applied to a surface of said transparent optical element, 
 wherein a diameter of said coating is smaller than an effective aperture of said optical system. 
 
   
   
     6. The lens barrel according to  claim 5 , wherein said transparent optical element is in the shape of a disc. 
   
   
     7. The lens barrel according to  claim 1 , wherein said ND filter comprises at least two portions having different optical densities. 
   
   
     8. The lens barrel according to  claim 1 , wherein said lens barrel comprises a zoom lens. 
   
   
     9. The lens barrel according to  claim 1 , wherein said lens barrel comprises a telescoping type zoom lens. 
   
   
     10. A lens barrel, comprising:
 an optical system including a short focal length for a wide angle of view; and 
 an ND coating applied to at least one lens element of said optical system; 
 
     wherein an optical density of said ND coating decreases in a direction radially outwards from an optical axis of said lens element. 
   
   
     11. The lens barrel according to  claim 10 , wherein said ND coating comprises:
 a high optical density portion in the shape of a circle which is positioned at a center of said ND coating; and 
 a low optical density portion positioned around said high optical density portion, 
 wherein a diameter of said high optical density portion is smaller than an effective aperture of said optical system. 
 
   
   
     12. The lens barrel according to  claim 10 , wherein said optical system comprises a plurality of lens groups, and
 wherein said ND coating is applied to a frontmost lens group of said plurality of lens groups. 
 
   
   
     13. The lens barrel according to  claim 12 , wherein said high optical density portion comprises at least two portions having different optical densities which are arranged concentrically with respect to said center of said ND coating. 
   
   
     14. The lens barrel according to  claim 10 , wherein said optical system comprises a plurality of lens groups, and
 wherein said ND coating is applied to a rearmost lens group of said plurality of lens groups. 
 
   
   
     15. The lens barrel according to  claim 10 , wherein said ND coating is in the shape of a circle having a diameter smaller than the an effective aperture of said optical system. 
   
   
     16. The lens barrel according to  claim 10 , wherein said ND coating comprises at least two portions having different optical densities. 
   
   
     17. The lens barrel according to  claim 10 , wherein said optical system comprises a plurality of lens groups, said ND coating being applied to one of said plurality of lens groups. 
   
   
     18. The lens barrel according to  claim 10 , wherein said lens barrel comprises a zoom lens. 
   
   
     19. The lens barrel according to  claim 10 , wherein said lens barrel is a telescoping type zoom lens. 
   
   
     20. A photographing lens comprising:
 a plurality of lens elements; and 
 at least one ND filter positioned on an optical axis of said plurality of lens elements, 
 wherein an optical density of said ND filter decreases in a direction radially outwards from said optical axis, and 
 wherein said ND filter is provided as a coating applied to at least one of said plurality of lens elements.